Lubricant



Patented July 28, 1942 UNITED STATES PATENT OFFICE LUBRICANT Stanley P. Waugh, Westfield, N. 1., asslgnor to Tide Water Associated Oil Company, Bayonne, N. .L, a corporation of Delaware No Drawing. Application January 10, 1941,

- Serial No. 373,875

6 Claims.

This invention relates to lubricant compositions and methods of preparing the same. More particularly, the invention is concerned with cutting oils, and especially with soluble oils such as those usedin metal working operations.

It is common practice to employ cutting oils in metal working or cutting operations and the like. In such operations it is necessary to minimize friction by the presence of a lubricating film, while at the same timeavoiding excessive temperature rise at the work area by continuously supplying a coolant in liberal quantity. So-called soluble oils are now commonly used for this purpose. Soluble oils so used are essentially aqueous emulsions of mineral oil in various degrees of dilution. These compositions have the advantage of supplying both lubricant and coolant in recovable combination permitting recirculation. In metal cutting, for example, the emulsion is applied in a continuously recirculated stream to the metal at the cutting area, the oil component forming a lubricant film between the cutting tool and the metal and the aqueous component effectively removing heat. 'I'hesecompositions have not been entirely satisfactory, however, because of the low strength and load-carrying capacity of the lubricant film.

, Means for increasing the load-carrying capacity of the lubricant film have been devised, one such means which has met with success being the incorporation into the mineral oil aqueous composition of saponified palm oil or the saponifled component derived from the fattyacid mixture obtainable from palm oil by treatment with alkaline material such as .triethanolamine. Such compositions are disclosed in my U. S. Patent 2,174,907. This patented composition obviates the necessity for the former practice of melting the palm oil prior to its use in cutting operations, eliminates waste -of palm oil and avoids other difiiculties which had been encountered in cutting operations.

It has now been discovered, according to the present invention, that certain additive substances containing phosphorus may beincorporated into cutting oils to provide mineral oil. compositionshaving greatly improved load-carrying capacity and other advantageous properties. Soluble oils are provided which permit cutting or other working of tougher'metals in shorter periods of time with resultant more rapid opera-- tion of metal working machines and extension of the field of use of soluble oils. The invention thus presents a material advantage to the modern machine shop in meeting demands for increased production of machined metal parts.

The type'or class of phosphorus compounds which according to the invention has been found particularly suitable for the stated purpose includes generally compounds or substances which may be formed by reacting phosphorus containing materials with compoundscontaining hydroxyl groups, such as phenols or alcohols. Phosphorus acid esters of the higher aliphatic alcohols or other phosphorus derivatives of the latter are particularly suitable, dilauryl phosphate being a representative example of such esters. Also corresponding thio phosphorus esters and derivatives are contemplated. Likewise, phosphorus derivatives of certain classes of compounds containing amino groups are effective, for example the reaction products of phosphorus acids and a1- kylolamines, a specific embodiment being the reaction product produced by reacting phosphoric acid with triethanolamine.

One surprising fact is that the stated phos-:

phorus compounds are materially effective in soluble oils in relatively small proportions. This fact, and the unusually high load-carrying capacity of soluble oils containing these substances,

indicates that these substances do more than increase the film strength of the lubricating oil; that they also impart extreme pressure properties. As is now believed in the automotivelubrication art, the efiectiveness of extreme pressure additives used in heavy duty extreme pressure gear lubricants is due to a chemical reaction involving the extreme pressure additive resulting in formation on the bearing surfaces of a high load-carrying film. Test results obtained in investigation of the soluble oils of this inven-.

tion.strongly indicate that the phosphorus conipounds employed perform a similar function.

High load-carrying properties aracharacteristic of soluble oils of this invention containing as little as 0.1% of the stated phosphorus compounds. The proportions may vary somewhat depending upon' the other constituents used in the composition and with the type of metal work ing intended; and itis therefore understood that the stated proportions are not to be considered as critical or limitative.

Another distinguishing feature or property of the phosphorus compounds of the type included by this invention is their compatibility with aqueous-oil emulsions of the type herein concerned.

Many substances are incapable of forming, or do 'not readily form, stable emulsions with water and oil, or if added to or incorporated in such emulsions will result in instability of suspended phases and cause the emulsion to break. Ob-

viously one of the important and essential requisities of soluble oils'is that they contain no constituent tending to cause emulsion instability, and

one of the objectives 'of the present invention is to provide stable soluble oil emulsions having markedly'high load-carrying capacity. The use of phosphorus compounds of the stated type does not adversely zaifect the stability of soluble oil emulsions and'in some cases actually results in increased stability. based upon discovery of the unexpected dual function of the stated phosphorus containing- As a general procedure soluble oil compositions according to the present invention are prepared additives in the composition.

by the usual method comprising bringing together suitable proportions of mineral oil and fatty acids, with heating if necessary, and as ub- The invention is therefore 51.1 parts by weight of a mineral red oil, from a goastalcrude, having a Saybolt viscosity of 300 seconds at 100 F., and 7.3 parts by weight ofp'alm oil having a fatty acid content of approximately"80%aby weight were mixed and the suitable for dilution with water for use in cutstance capable of forming withthe fatty acida soap which acts as the emulsifying agent. The

varies somewhat with the individual compound selected for use. Phosphorus containing compounds soluble in mineral oil,.-for example di-l lauryl phosphate, may be added to the mineral oil composition just described and the resulting product marketed'as a'soluble oil which before use is incorporated with water to form an emulsion. Someof the phosphorus compounds, for example the phosphoric acid-triethanolamine'reaction product mentioned above, are of relatively low solubility in mineral oil but are soluble in water. These are preferably incorporated with the described composition of mineral oil and soap with addition of water. Water "may be I added in proportions sufficient to make a ready- 'e emulson or in lesser quantities to form'an toemulsion in concentrated -form-which"can* be method: of incorporatingthe phosphorus compounds of the-invention into the composition ting or other metal working operations.

Example I! 52.5 parts by weight of the mineral oil and 7 .3 parts by weight of the palm oil described in ExampleI were mixed and heated in the manner describedin, Example I at a temperature of about 160? F. until the palm oil had all dissolved. To this solution was added 1.6 parts by weight of a commercial product consisting essentially of dilauryl phosphate and known as Du Pont Ortholeum 162 or G. D. 162" (obtainable from E. I. Du Pont de Nemours & Company), 3;6-parts by weight of triethanolamine and 35.0 parts by weight of water were then added with stirring to'the hot solution in the manner described in ExampleLJ r i The resultingcomposition which when cooled marketed as'such and diluted with water before v use. Of course the oil solublephosphorus compounds such as dilauryl phosphate may also be incorporated with water asdescribedand marketed as concentrated or diluted'emulsion if desired.

While it isto be understood that the invention includes within its scope theemployment of' the stated phosphorus compounds in cutting'oils' or soluble oils generally,'and is not limited to" their use in soluble oils of particular composition, it is preferred to employ these additive agents in soluble oils containing palni' oil'soaps of the-type set forth'in my aforementioned U. S. Patent No. 2,174,907 in order that'th'e advantageous results ensuing from said compositions may In this respect the present invention may be considered an improvement over that ofmy stated patent. Therefore, the following illustrative examples setting forth specific embodiments of the present inventioncontaining palm oil ,products are not intended to constitute limitations as to scope of invention,- but are to be considered as preferred embodiments. i a

7 Example! 4 18.5 parts by weight of phosphoric acid were added'to 22.5 parts by weight" of triethanolamine and the mixture was heated gently. The re- 1 action product when dried appeared as a waxy,

solid material which was readily soluble in water.

This reaction product was incorporated into a soluble oil of the type set forth in my stated U. S. patent as follows. 7

be attained.

was of' the consistency of a paste consisted of a stable soluble oil emulsion suitable for use in cutting and other metal working operations upon dilution with suitable-amountsof water.

I E xample Ill Another soluble {.oil composition was prepared using the same starting materials and in'the same manner as described in Example 11 except that instead of 1.6 parts by weight of the dilauryl phosphate compound, 2.7% of said compound was used. A stable concentrated emulsion suitable for'dilution resulted.

'Ihe products produced as in the above examples have enduring stability of emulsion upon storage and exposure to temperature extremes.

In order to obtain an indication of the relative load-carrying'capacities of the solubleoil compositions of the invention they were subjected to test on the Timkin testing machine. The Timkin machine comprises a ring of carbon steel fastened to a mandrel which is rotated and a carbon steel block having a flatsurface'which is placed directly beneath the rin and adapted to be pressed upwardly against the ring by a pivoted lever arm. The lubricant to be tested is made toflow continuously between the block and rotating ring, and. during the test weights -of successively increasing magnitude are placedupon the endof the lever arm, thus increasing the force between thering and block. After running the machine for a given period the block is removed and the scar produced by the revolving ring on the surface of theblock' is measured. From this measurement and from the weight re quired and characteristics of the lever arm, the pressure whieh'the lubricant was able to withstand iscomputed. r

Portions of each of the concentrated emulsions prepared as in'Examples' I, II and 111 were diluted, with stirring, with ten parts of water and the resulting diluted emulsions were .tested on the Timkin machine in the manner described hereinabove, the ring being revolved at 600 R. P. M., which corresponded to a speed of the rubbing surface of the ring of 300 feet per minpte. With each load impressed during the runs the machine was run for a five minute interval and when such load had been reached which caused failure of the oil, terial scoring of the block, the run was terminated.

The following table shows the pressures at failure of the soluble oils of Examples I, 11 and III, diluted as described, as compared with a similar soluble oil prepared from palm oil, mineral oil, triethanolamine as described in my U. S.

Patent No. 2,174,907 but containing no phosphorus compound (designated in the table as A"), and palm oil alone (designated as B), which compositions were on the Timkin machine.

Table Load at failure Composition pounds per sq. in

29, 000 27, 000 32, 000 to 34, 000 15, 000 to 17, 000 20, 000 to 21, 000

These comparative results show the superior effectiveness of the soluble oils of this invention. These data are particularly significant in demonstrating the increased load-carrying capacity of the soluble oils of the invention over compositions "A" and B, which latter compositions heretofore have been considered especially effective as regards load-carrying properties.

The examples hereinabove are not intended to constitute limitations as to the scope of the invention regarding use of anyparticular phosphorous compound in lubricants of the type discussed herein. Other phosphorus compounds than those shown have been tested and found efas' evidenced by maalso tested as set forth,

fective. Among these may be mentioned tricresyl phosphate and other aromatic phosphorus containing substances. Likewise, mixtures of difierent phosphorus containing materials incorporated in soluble oils For example, incorporation of both dilauryl phosphate and the stated phosphoric acid-triethanolamine reaction product in soluble oils containing saponifled palm oil such as those of my stated U. S. Patent No. 2,174,907 produces particularly effective stable emulsions for the stated purpose.

Iclaim:

l. Lubricating composition suitable for use in metal working operations, which comprises a stable aqueous emulsion containing mineral oil, a saponifled component derived from the fatty acid mixture obtainable from palm oil, and a phosphorus-"containing substance effective to increase the load-carrying capacity of the composition.

2. Lubricating composition suitable for use in metal working operations which comprises a stable aqueous emulsion containing saponified palm oil, mineral oil and a reaction product of a phosphorus acid and a hydroxy organic compound, said reaction product having high loadcarrying properties. I

3. Lubricating composition as in claim 2', in which the reaction product is a phosphoric acid ester. 7

4. Lubricating composition as in claim 2, in which the reaction product is produced by reacting' phosphoric acid and an alkylolamine.

5. Lubricating composition as in claim 2, in

product is produced by react- I characteristics. v

STANLEY P. WAUGH.

have been found effective. 

